This fast 55mm screwmount lens existed in several versions all with the same optical diagram. From the 1965 version, at least one of the glass elements is made from radioactive glass which yellows over time. While the optical diagram remained unchanged, tweaks to the optics (surface curvature, distance between elements) can't be precluded when Pentax switched glass type.

Here is an overview of the variants that we're aware of:
1: Takumar 55mm F1.8
2: Auto-Takumar with semi-automatic diaphragm
3: Auto-Takumar with automatic diaphragm. The direction of the aperture ring was reversed as was the norm on early lenses. This lens was soon re-released as a Super-Takumar with some design changes to the barrel
4: Super-Takumar with fine ribs on the aperture ring and reversed direction of the aperture ring
5: Super-Takumar still with fine ribs on aperture ring, but the ring now turns the "right" way (has the F1.8 position to the right) as all later M42 lenses
6: Super-Takumar with coarse ribs on aperture ring
7: Super-Multi-Coated Takumar
8: SMC Takumar with open aperture metering

1: Takumar 55mm F1.8 (this lens)
2: Auto-Takumar with semi-automatic diaphragm
3: Auto-Takumar with automatic diaphragm
4: Super-Takumar with fine ribs on the aperture ring and F16 to the right
5: Super-Takumar with fine ribs on the aperture ring and F16 to the left
6: Super-Takumar with coarse ribs on aperture ring and F16 to the left
7: Super-Multi-Coated Takumar
8: SMC Takumar with open aperture metering

Auto-Takumar, first version (4th photo above):

Auto-Takumar 55mm F1.8 (early)

Image FormatFull-frame / 35mm film

Lens MountM42

Aperture RingYes

DiaphragmSemi-automatic, 10 blades

Optics6 elements, 5 groups

Mount VariantM42 Stop-down Pin

Max. ApertureF1.8

Min. ApertureF22

FocusingManual

Min. Focus
55 cm

Max. Magnification
0.13x

Filter Size46 mm

Internal FocusNo

Field of View (Diag. / Horiz.)

APS-C: 29 ° / 25 °
Full frame: 43 ° / 36 °

Hood

Case

Lens Cap

Coating

Weather SealingNo

Other Features

Diam x Length

Weight174 g

Production Years
1958
to 1960

Engraved Name
Auto-Takumar 1:1.8 f=55mm

Variants

1: Takumar 55mm F1.8
2: Auto-Takumar with semi-automatic diaphragm (this lens)
3: Auto-Takumar with automatic diaphragm
4: Super-Takumar with fine ribs on the aperture ring and F16 to the right
5: Super-Takumar with fine ribs on the aperture ring and F16 to the left
6: Super-Takumar with coarse ribs on aperture ring and F16 to the left
7: Super-Multi-Coated Takumar
8: SMC Takumar with open aperture metering

Auto-Takumar, second version (3rd photo above). Despite the name Auto-Takumar this lens has a fully automatic diaphragm like the later Super-Takumar lenses. The aperture ring turns the opposite way compared to all later lenses:

Auto-Takumar 55mm F1.8 (late)

Image FormatFull-frame / 35mm film

Lens MountM42

Aperture RingYes

DiaphragmAutomatic, 6 blades

Optics6 elements, 5 groups

Mount VariantM42 Stop-down Pin

Max. ApertureF1.8

Min. ApertureF16

FocusingManual

Min. Focus
45 cm

Max. Magnification
0.17x

Filter Size49 mm

Internal FocusNo

Field of View (Diag. / Horiz.)

APS-C: 29 ° / 25 °
Full frame: 43 ° / 36 °

Hood

Case

Lens Cap

Coating

Weather SealingNo

Other Features

Diam x Length

Weight215 g

Production Years
1960
to 1962

Engraved Name
Auto-Takumar 1:1.8/55

Product Code
345

Notes
This lens has an automatic diaphragm like the later Super-Takumar lenses. The physical design was also close to that of the Super-Takumar with the aperture ring next to the lens mount. The aperturering has the smallest F-stop to the right, not to the left.

Variants

1: Takumar 55mm F1.8
2: Auto-Takumar with semi-automatic diaphragm
3: Auto-Takumar with automatic diaphragm (this lens)
4: Super-Takumar with fine ribs on the aperture ring and F16 to the right
5: Super-Takumar with fine ribs on the aperture ring and F16 to the left
6: Super-Takumar with coarse ribs on aperture ring and F16 to the left
7: Super-Multi-Coated Takumar
8: SMC Takumar with open aperture metering

Super-Takumar, first version. This version can be recognized on its fine ribs on aperture ring and that the smallest F-stop (F16) is to the right on the ring:

Super-Takumar 55mm F1.8 (early)

Image FormatFull-frame / 35mm film

Lens MountM42

Aperture RingYes

DiaphragmAutomatic, 6 blades

Optics6 elements, 5 groups

Mount VariantM42 Stop-down Pin

Max. ApertureF1.8

Min. ApertureF16

FocusingManual

Min. Focus
45 cm

Max. Magnification
0.17x

Filter Size49 mm

Internal FocusNo

Field of View (Diag. / Horiz.)

APS-C: 29 ° / 25 °
Full frame: 43 ° / 36 °

Hood

Case

Lens Cap

Coating

Weather SealingNo

Other Features

Diam x Length

Weight215 g

Production Years
1962
(start of production)

Engraved Name
Super-Takumar 1:1.8/55

Product Code
345-2, 345-5, 33450, 34520

Notes
Fine ribs on aperture ring.The aperture ring has the smallest aperture to the right, i.e. the ring turns the opposite way of later models.The lens has a dot rather than a diamond as the settings mark.

Variants

1: Takumar 55mm F1.8
2: Auto-Takumar with semi-automatic diaphragm
3: Auto-Takumar with automatic diaphragm
4: Super-Takumar with fine ribs on the aperture ring and F16 to the right (this lens)
5: Super-Takumar with fine ribs on the aperture ring and F16 to the left
6: Super-Takumar with coarse ribs on aperture ring and F16 to the left
7: Super-Multi-Coated Takumar
8: SMC Takumar with open aperture metering

Super-Takumar, second version. This version can be recognized on its fine ribs on aperture ring and that the smallest F-stop (F16) is to the left on the ring:

Super-Takumar 55mm F1.8 (ii)

Image FormatFull-frame / 35mm film

Lens MountM42

Aperture RingYes

DiaphragmAutomatic, 6 blades

Optics6 elements, 5 groups

Mount VariantM42 Stop-down Pin

Max. ApertureF1.8

Min. ApertureF16

FocusingManual

Min. Focus
45 cm

Max. Magnification
0.17x

Filter Size49 mm

Internal FocusNo

Field of View (Diag. / Horiz.)

APS-C: 29 ° / 25 °
Full frame: 43 ° / 36 °

Hood

Case

Lens Cap

Coating

Weather SealingNo

Other Features

Diam x Length

Weight215 g

Production Years
to 1965

Engraved Name
Super-Takumar 1:1.8/55

Product Code
34520 (?)

Notes
Fine ribs on aperture ring.The aperture ring has the smallest aperture to the left as on later lenses.

Variants

1: Takumar 55mm F1.8
2: Auto-Takumar with semi-automatic diaphragm
3: Auto-Takumar with automatic diaphragm
4: Super-Takumar with fine ribs on the aperture ring and F16 to the right
5: Super-Takumar with fine ribs on the aperture ring and F16 to the left (this lens)
6: Super-Takumar with coarse ribs on aperture ring and F16 to the left
7: Super-Multi-Coated Takumar
8: SMC Takumar with open aperture metering

Super-Takumar, latest version. This version has coarse ribs on aperture ring (last photo):

Super-Takumar 55mm F1.8 (late)

Image FormatFull-frame / 35mm film

Lens MountM42

Aperture RingYes

DiaphragmAutomatic, 6 blades

Optics6 elements, 5 groups

Mount VariantM42 Stop-down Pin

Max. ApertureF1.8

Min. ApertureF16

FocusingManual

Min. Focus
45 cm

Max. Magnification
0.17x

Filter Size49 mm

Internal FocusNo

Field of View (Diag. / Horiz.)

APS-C: 29 ° / 25 °
Full frame: 43 ° / 36 °

Hood

Case

Lens Cap

Coating

Weather SealingNo

Other Features

Diam x Length59 x 38 mm

Weight215 g

Production Years
1965
to 1971

Engraved Name
Super-Takumar 1:1.8/55

Product Code
371, 37100, 37101

Notes
Coarse ribs on aperture ring

Variants

1: Takumar 55mm F1.8
2: Auto-Takumar with semi-automatic diaphragm
3: Auto-Takumar with automatic diaphragm
4: Super-Takumar with fine ribs on the aperture ring and F16 to the right
5: Super-Takumar with fine ribs on the aperture ring and F16 to the left
6: Super-Takumar with coarse ribs on aperture ring and F16 to the left (this lens)
7: Super-Multi-Coated Takumar
8: SMC Takumar with open aperture metering

Super-Multi-Coated Takumar (1st photo above):

Super-Multi-Coated Takumar 55mm F1.8

Image FormatFull-frame / 35mm film

Lens MountM42

Aperture RingYes

DiaphragmAutomatic, 6 blades

Optics6 elements, 5 groups

Mount VariantM42 Stop-down Pin

Max. ApertureF1.8

Min. ApertureF16

FocusingManual

Min. Focus
45 cm

Max. Magnification
0.17x

Filter Size49 mm

Internal FocusNo

Field of View (Diag. / Horiz.)

APS-C: 29 ° / 25 °
Full frame: 43 ° / 36 °

Hood

Case

Lens Cap

CoatingSMC

Weather SealingNo

Other Features

Diam x Length

Weight239 g

Production Years
1971
to 1972

Engraved Name
Super-Multi-Coated TAKUMAR 1:1.8/55

Product Code
37104, also 37101 and 37106 have been reported

Variants

1: Takumar 55mm F1.8
2: Auto-Takumar with semi-automatic diaphragm
3: Auto-Takumar with automatic diaphragm
4: Super-Takumar with fine ribs on the aperture ring and F16 to the right
5: Super-Takumar with fine ribs on the aperture ring and F16 to the left
6: Super-Takumar with coarse ribs on aperture ring and F16 to the left
7: Super-Multi-Coated Takumar (this lens)
8: SMC Takumar with open aperture metering

SMC Takumar (2nd photo above). This final version has a rubberized focus ring and open aperture metering with the Spotmatic F, ES and ESII:

1: Takumar 55mm F1.8
2: Auto-Takumar with semi-automatic diaphragm
3: Auto-Takumar with automatic diaphragm
4: Super-Takumar with fine ribs on the aperture ring and F16 to the right
5: Super-Takumar with fine ribs on the aperture ring and F16 to the left
6: Super-Takumar with coarse ribs on aperture ring and F16 to the left
7: Super-Multi-Coated Takumar
8: SMC Takumar with open aperture metering (this lens)

This is a great 55mm flower or portrait lens. I have the most recent SMC version. Bokeh and colors are what I like about it, along with compact size. Bokeh is on par with the 50mm f1.4. Different, but both good. This is not the sharpest of the 50-is mm focal length though it's still "sharp." That's why I use it for portraits mostly. I also have the SMC K mount 50mm f1.2, SMC K mount 50mm f1.4, M 50mm f2, and Super-Takumar 55mm f1.8. For flowers, this is the one I like. A little bit longer, plenty fast, and small. It's not a good landscape lens because it loses image quality betweek f13 and f16, and lacks an f22 stop entirely. Use the M or A series 50mm f2 instead for that.

For anyone wanting to compare all the different vintage 50mm's from Pentax, you need not collect them all... I've posted a fairly comprehensive video comparison of them while comparing for myself:

If an old M42 lens is in the running for the next purchase due to LBA......this might just be a no regrets purchase.

My Super-Takumar (late version) came with a Pentax S3 in a bundle that included a Tamron P-KA adapter which might sell for half the original cost of that bundle making this lens cost less than the $40 value I have given it.
Apart from the awkward Auto-Manual switch (awkward in comparison to others like the Helios -44M) the lens is amazing. It may not be as sharp as more costly lenses but it has great (and typical) Pentax attributes.
Here is an image taken when trying it out last year (along with a crop).

This is my first manual "vintage" lens.
I bought it online and it arrived in good condition.
Eager to try it I went to the local park to shoot some pics.
Very impressive. Sharp, light, easy to handle, even for a guy like me in the habit to relay on autofocus and auto exposure.
It gave me back the joy of studying a little bit before pressing the shutter and started, I believe, a new passion for all manual lenses.
Here few samples all at 1,8.

I'm rating the Super-Multi-Coated Takumar 55mm/1.8. It came attached with a Spotmatic that I bought to get my daughter interested in film cameras. I already owned an SMC Takumar 55/1.8 (the later version).

My Super-Multi-Coated Takumar 55mm/1.8 is either a rare and special one... or this lens design as a whole is just incredible. I simply cannot believe how good this lens is even on my Sony A7r, which is unforgiving. It's not really usable at f/1.8 (soft, glowy, bad corners). Even f/2.8 is a bit dodgy. By f/4 the centre is nice and sharp, but corners are still soft. By f/5.6 I'm only worried about extreme corners if something really important is happening there. By f/8 I'm not worried about the corners anymore. Incredibly, it's still entirely usable at f/16; there's definitely a bit of diffraction, but if I need depth of field more than I need sharpness I'll use f/16 and be happy. I find the out of focus areas to be a bit nervous. There's a bit of purple fringing at f/1.8, which is gone by f/4.

Like the other Takumars in this design, it's an all metal beauty. The focus ring is beautifully damped and the aperture ring clicks smoothly. In comparison, my SMC Pentax K lenses feel rough and clunky.

My main 55mm lens is my SMC Pentax-A 645 45-85mm, which weighs a ton and lives on my Mirex tilt/shift adapters. The Takumar 55/1.8 is my everyday lens. I did a side-by-side comparison recently, and yes, the professional-grade 645 lens is of course better in every way -- but the Takumar is still amazingly good. I wouldn't hesitate to use it for critical work if I didn't have my big 645 handy.

I just recently got this lens and have been shooting with it as much as possible; so far it has been awesome. For me personally, this lens is just slightly annoying to focus because my left hand always hits my right hand when I'm focusing, that's why it got 9 for handling, but again, thats just me. I love this lens, this was my first lens at such a wide aperture, so I was a bit weary of having to focus with it, but it's super easy, and very smooth. I highly recommend to everyone!

Well, i think now i can share my experience with my Takumar 55 1.8.
First of all, sorry if my english isn't very good.
Second of all, this should be the legendary normal range takumar, not the 50 1.4.
Mine is the Super-Multi-Coated version. I use it with a hood always, so i can't speak if it's flare prone.
This lens is superior to my SMC 50 1.4. It's more precise, have more sharpness, better bokeh at the same aperture.
It's commom enough to have incredible prices. For canon users it's the best bang for buck out there. Using the af chip guarantees incridible shots. It's no sharper than the 50mm f1.8 II, but have better bokeh and it's somewhat more beaultiful.
I've bought a spotmatic f and i like it very much because of it's precision in focusing. My SMC Takumar 50 1.4 have the advantage of open aperture metering, but focusing wide open with a 1.4 lens is a pain, because it is'nt sharp enought to nail focus quickly. I always have some doubt's if i can focus more acurately.

Well all I can say is if I found this one first I probably would not own two takumar 50mms, They are all great lenses, but sometimes you want circular bokeh and a fair amount of micro-contrast or whatever they call that, all I can say about this is wow, Mine is the super takumar, no multi-coating, yet it has a rubber ring, how odd. it flairs like crazy, but everything else is so good on this lens I will work around it. Unless I am worried about flair I think it is my new main lens. If you are thinking about getting the tak 50mm f1.4, well still get it, it rocks, but if you are not to sure if you want to go the MF rout, by this one for $20 bucks, it is every bit as good as it's sister lens.

Surprisingly great lens(1965: Super-Takumar 1:1.8/55 (second version)). I purchased this lens in almost mint condition for $35. I wasn't expecting much despite the stellar reviews but I got to admit, this lens is highly underrated. It is relatively sharp starting from f1.8 and then becomes razor sharp after that. I gave it a '9' as far as sharpness, but that's after comparing it to my 20-40mm and my 35mm Macro. I wish I could give it a 9.5 or something.

For portraits it's absolutely great and gives me that extra 5mm missing from my 50m f1.4. So how does it compare to the very popular 50mm f1.4 ? This lens holds it's own and then some falling short by a slight amount of pixel dust and character coming from the f1.4.

The build is about the same as the f1.4. Same old Takumar all metal frame, buttery smooth focus ring and snappy but tight aperture ring. The lens weighs a little bit more for its size than the DA and FA lenses, but I don't mind the weight at all. As a matter of fact it makes it feel as if I'm carrying a precise and expensive instrument in my hand not a toy(IMHO).

How does it compare to the very popular 50mm f1.7 that in my opinion is highly overrated ? This lens is another league maybe not in sharpness, but in every thing else and I own both lenses.

I bought a copy and it was not sharp, but reading the reviews I figured I had a bad one. I bought a second copy, same thing, not sharp until f5.6 and then not really great. I am not going to buy a third. I give up. Both lenses were SMC, first one was on old version and the second was a new version. Come think of it I had a third version that came with my Spotmatic in the 70's. It must not have been very good either because I always used the 85 and 35.

I recently got this lens which I am using on a Sony a6000 through m42 adapter - seen in pic. I agree with previous reviewers - a very nice lens! Contrast is great, Bokeh is very good. A bit softness in corners (at least on mine) until stopped to 4. Does it flare? Absolutely but it should be expected. Still, use mine without hood and unless sun hits the rear element I haven't been troubled much.

I guess my version is -71? making it +40 years old... which staggers at least my mind.
I paid about 28 bucks in Scandinavia for mine, in good working condition. Pretty normal price I guess, but I treasure it already for being such a joy to use and delivering really nice results!

Near perfect for what it is. I still use the excellent kit lenses for convenience but I enjoy hanging this jewel on the K-500 and making pretty portraits and getting creative. I have the Super-Multi-Coated TAKUMAR 1:1.8 / 55mm.

My very first screw-mount lens, using a genuine Asahi Pentax adapter on my K-30 (a cheap adapter with a protruding flange will prevent the lens from focusing to infinity, as noted by the reviewer below).

This is my experience with the lens after using it for a month during the Single In December 2014 challenge here on PentaxForums.

First of all, the lens is tiny. Minuscule. Build quality is excellent, as expected. The lens is fully functional and appears to be very clean, but there is some grittiness towards the infinity end of the focus throw.

I loved the real-time aperture effect through the viewfinder. Yeah, the viewfinder darkens as you stop down, but it really wasn't too much of a hassle when the ambient light was bright enough, and I could just flip the switch between Manual and Auto to jump back and forth between wide-open for focusing, and whatever aperture I thought was appropriate for DoF.

Focusing was easy and fast; f/1.8 seems to be a good aperture for easy focusing. I was satisfied with the lens' performance at infinity and minimum focusing distance (about 18 inches).

The IQ from the lens is stellar. Great contrast, nice colors, very sharp. The bokeh was good, but it wasn't knocking my socks off. I'm not a junkie for "creamy dreamy" backgrounds, so it's not a deal-breaker for me, and the isolation from the shallow DoF was perfectly sufficient. I don't recall noticing much of any CA/fringing at all, and the colors all seemed true-to-life. There really wasn't a whole lot that needed to be done in PP, but I like to try different things once I get the images on my computer, anyway. It seems to be a flattering lens for portraits, and is a good length for such. I thought it would be "too long" for Christmas snaps, but it turned out to be pretty perfect in a moderately-sized family room.

The lens' performance didn't really blow me away; I've been using normal/short tele lenses since July and I'm kind of burnt out on them... BUT: After it's all said and done, I enjoyed using the lens very much for December. I can tell that I enjoyed it because it didn't really cross my mind to change it. Today I put another lens on to get a shot, and I had totally forgotten that this was a screw-mount with an adapter. I was standing there, looking out the window at the sunrise, idly pressing the lens release button and turning... and... Oh yeah! Ha! Not all lenses can satisfy me so they just sit on my camera for weeks without me thinking I need something wider or longer or whatever. Kudos to the SMC Takumar 55/1.8.

It is a great all-around performer with better than average IQ. I really enjoyed the focal length, and the manual aperture was a joy. It's a compliment to my collection of lenses, and a piece of glass I'm glad to have, but it's not a night-and-day difference from my other "Fast Fifties". Use it, and enjoy the experience. Repeat with all your other lenses. :-)

I would give this lens a PERFECT 10 in every category but .. I did not ask questions when purchasing it on E-bay that would have stopped the buy ..
Since I have a K-mount Body (K-30) .. I had to purchase a screw mount adapter and did so (Pro-Optics) .. the adapter fit the lens perfectly and the combination fit my K-30 perfectly .. first shots were at fairly close range (within a 16 foot room) .. gorgeous sharp .. but then I aimed out a window and could not focus to infinity .. could not focus on a wall 30 feet away .. not even close ..
I am thinking it is NOT the lens but more likely the lens combination with adapter (no glass) and the K-mount body .. because from a couple feet out to about 16 feet it is perfect.

My copy is the last version SMC TAKUMAR 1:1.8/55
Cheapest lens I ever bought and one of the best. Love the classic Pentax colours. Wide open it makes an excellent portraite lens. Stopped down a little and becomes as sharp as you will ever need. There is absolutely no reason not to own this lens.

Own definition of points - using the above scaling: 5 = still good, 7-8 = good to very good, 9-10 = excellent(10 = "100%" for technical aspects: such a immaculate thing does not exist)

The 1971 S-M-C Takumar 1:1.8/55 is a wonderfully built optics, the mechanical quality needs not shy in compare to a Summilux for
example. Although the optical properties of these Japanese mass products do not quite reach - but also the more modern - Western
Zeiss or Leitz quality of complex, individual centering small and therefore expensive series (the measure of all my things are the
excellent Summilux-M(R) 1:1.4/50mm and the Planar 1.4/50mm. However, if you think of the price-performance ratio ...)

I have restored my copy, because it had some fungus behind the front lens and was dusty inside, and the lens capsulated unit had
come loose. For a more than 40-year-old and formerly often used lens this is not abnormal and you can get in this way a great piece
of optics for pocket money. The defects were easy to fix and the glasses are otherwise perfectly (the radioactive caused yellowing
of the rear lens group(s) is strangely not very pronounced, the glass mushroom was able to live well in any case ...)

This lens and the SMC Pentax-M 1:1.7/50mm are now my favorite - Pentax - normal focal lengths for close-ups, a comparison of the
two lenses could therefore be of interest. The following test shots were taken at f/3.5 (step between f/2.8 and f/4) on Canon APS-C
sensor, in this aperture both lenses have a desired better resolution than full aperture, and at the same time a certain ability to exempt
the object.

About Sharpness and Aberrations: this is a re-evaluation and the result of many new photos that have recently arisen with this copy
(a later purchased copy in a very good condition showed exactly the same optical properties).
Spherical and chromatic aberration defects have been corrected excellent at f/4 over the entire image field, also at the borders with
extremely high contrast there is surprisingly marginal flare visible. The for comparison used SMC Pentax-M 1:1.7/50mm features under
all conditions visible better sharpness resp. contrast, probably a result of more advanced types of glass and coatings - however, the
charm of the older lens is thus not diminished.

The cut-outs have all the same size, so you can also see the difference between the 55/50mm focal lenght.

The old lenses with modern adapters and common lens hood:
In reconditioning damages and scratches on the surface of the 1:1.8/55 were treated something cosmetically ...
(Right above the second copy of S-M-C Takumar 1:1.8/55)